PD output feedback control design for robot manipulators: Experimental results

In this paper, we design and implement model independent observer-controller based output feedback method for robot manipulators. The control design uses only proportional and derivative (PD) error terms for trajectory tracking of nonlinear robot manipulators. The unknown velocity signals is generated by the output of the linear observer. The design is very simple in the sense that it does not require a priori knowledge of the system dynamics. Using Lyapunov-like energy functional, tracking error signals under PD output feedback design are shown to be bounded and their bounds can be made arbitrarily small by using observer-controller design parameters. These arguments are experimentally verified on a 3-DOF Phantom™ haptic robot device.